A boom support vehicle is a trailer attached to the boom of a crane for the purpose of supporting a portion of the weight of the boom of the crane when using a crane carrying vehicle to move the crane over roadways. The additional axles provided by the boom support vehicle take some of the crane's heavy weight, thereby lowering the per axle load exerted on the roadway to a level which is within regulatory limits. The boom support vehicle also takes boom-related forces that result from the crane carrier and boom support vehicle going into and coming out of a turn. As cranes have increased in size, boom support vehicles have necessarily been modified to accommodate these larger loads. For example, boom support vehicles have been equipped with hydraulic suspension and better boom-to-vehicle connections to better travel safely on the highway at higher speeds. Typical boom support vehicles include articulated front and rear dollies which have conventional axles. The dolly tower is rigidly connected to the elongated load and pin connected to the top surface of the boom support vehicle by lateral pins to allow the dolly to pivot in a fore and aft direction.
However, when the crane carrying vehicle, crane boom, and boom support vehicle attempt to move in a reverse direction, the articulated boom support vehicle will quickly steer in one direction or the other (i.e. “jack knife”). As such in present designs the boom support vehicle is locked so that it cannot pivot. This however can produce large torsional forces into the boom support vehicle and the boom and also forces that will make the crane carrier, crane, and boom support vehicle steer in unpredictable directions.